//
// Created by hsj on 2024-1-11.
// 多播基于UDP;多播组是D类IP地址( 224.0.0.0~ -239.255.255.255 )
// D类地址224.x.x.x~239.x.x.x


#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include <fcntl.h>

#ifdef WIN32
//windows minGW64
//inet_pton函数：_WIN32_WINNT
#ifdef _WIN32_WINNT
#undef _WIN32_WINNT
#endif
#define _WIN32_WINNT 0x0600
#include <winsock2.h>
#include <ws2tcpip.h>
//#pragma comment(lib,"ws2_32.lib")
#else
//linux  gcc
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/select.h>
#endif
#define BUF_SIZE 30
void error_handling(char *buf);
int main(int argc,char *argv[]){
    int recv_sock;
    int str_len;
    char buf[BUF_SIZE];
    struct sockaddr_in adr;
    struct ip_mreq join_adr;
    char ip[]="224.1.1.2";
    char port[]="3344";

    recv_sock=socket(PF_INET, SOCK_DGRAM,0);
    memset(&adr, 0, sizeof(adr));
    adr.sin_family=AF_INET;
    adr.sin_addr.s_addr=htonl(INADDR_ANY);
    adr.sin_port=htons(atoi(/*argv[2]*/port));

    if(bind(recv_sock, (struct sockaddr*) &adr, sizeof(adr))==-1)
        error_handling("bind() error");

    join_adr.imr_multiaddr.s_addr=inet_addr(/*argv[1]*/ip);//多播组IP
    join_adr.imr_interface.s_addr=htonl(INADDR_ANY);//本机IP
    setsockopt(recv_sock, IPPROTO_IP,IP_ADD_MEMBERSHIP, (void*)&join_adr, sizeof(join_adr));

    while(1){
        str_len=recvfrom(recv_sock, buf, BUF_SIZE - 1, 0, NULL, 0);//区别UDP
        if(str_len<0)
            break;
        buf[str_len]=0;
        printf("%s\n",buf);
    }
    close(recv_sock);

    return EXIT_SUCCESS;
}

void error_handling( char *message){
    fputs (message, stderr);
    fputc('\n', stderr);
    exit(1);
}